i have a 98 civic ex w/ a 1.6 vtech

problems when i start it it idles very low and vibrates the car, reves up fine but goes back down to a very low idle.

sometimes ill go to start it and it stalls and smells like gas. so i start it again and it takes a bit for it to start. and it wont idle at all...

i replaced the idle air control valve on the back of the intake with the 2 coolant hoses going to it. and no change in idle.

i tried adjusting the throttle cable. but that makes it idle to high.


any ideas?

 

there is a screw on the throttle body (on the very top of it) take a flat blade screw driver and try turning it to the left (opening it)

also, try to check your TPS (throttle position sensor) with a voltmeter. it tells you how to measure the volts in the Haynes manual (you can get both the voltmeter and the haynes manual at your local auto parts store)

good luck!

 

Make sure all your vacuum hoses are correct, and that the PCV is not clogged, the engine gets about 40% of its idle air from air in the crankcase. If thats all good, see below.


Unplug your IACV with the engine running full warm, and hold the throttle open if you have to and turn the idle screw outwards, until your engine idles smoothly at 450rpm. Once that idle is achieved, plug the IACV back in, and the engine should idle at specified rpm. (670-750rpm)

 

it idles really rough when it idles low. and the a/c kicks on and off when its at an idle. i always have to keep it reved up at a red light to keep cold a/c

 

Is it misfiring, or is the check engine light on? If so, check out this link:

https://honda-tech.com/zerothread/1901557

 

Did you try setting the idle using the throttle plate adjustment with the IACV unplugged? There's a procedure for doing this in the Helms manual. The IACV can only do so much.

 

no i didnt do it with the iac unplugged. ill do that next. and yes my cel is on. but because the kid i bought the car off of took the cat off it.

 

did you check the CEL codes?

 

yes i checked the codes. it was insufficient catalyst.